The capacity of a magazine on an automatic weapon places a constraint on the number of rounds which may be fired between reloading operations. Magazines for hand-carried weapons have generally been limited by the weight of the magazine and its contained rounds to spring-load magazines having a capacity of a few dozen rounds.
The recent trend to smaller and lighter ammunition such as, for example, 5.56 mm cartridges, permits a single operator to carry enough ammunition mounted on the weapon to make belt-type feed very attractive if it could be readily loaded by an upright walking operator carrying the weapon. Since one of the operator's hands is occupied supporting the weapon, any reloading operation must be accomplished by his single remaining hand. Furthermore, besides mounting the ammunition, it should be made ready for firing preferably by the mere act of mounting the magazine containing the ammunition on the weapon.
Linked belt fed machine gun systems in the prior art have required one or two separate additional actions by the operator in order to load. These additional actions consisted of pulling, pushing or otherwise positioning the leading portion of an ammunition belt by hand into a specific part of the weapon mechanisms. Ordinarily, these systems additionally required at least one further action by the operator such as, for example, holding the leading portion of the belt in its proper position by closing a door or by otherwise engaging a latching or holding mechanism prior to being ready to charge and fire. Such additional acts prevented the rapid mounting and firing of linked belt ammunition by an upright operator carrying the weapon. That is, these additional operations require two hands. Since one hand of the erect walking operator is engaged in carrying the weapon, he was not able to perform the additional acts without laying the weapon down.